Automatic backstop for motor vehicles



June 11, 1929. P. LACY AUTOMATIC BACKSTOP FOR MOTQR VEHICLES Filed Nov, 29, 1921 ATTORNEY WITNESS:

. rounds the sleeve and a fork 9 has its rongs preventing the vehicle from rolling Patented 11, 192 9 PATENT OFFICE},

v rm n. LACY, or nos morass, camroama.

an'ron'rrc nacxs'ror roa Boron vnnrcrns.

Application filed November This invention relates to an automatic back stop for motor vehicles, the general object of the-invention being to provide meanis fir ac wardly when the gears are in any posltion except in reversing position, with means for holding the lock ng means of the back stop in neutral position 'when the gear shifting lever'is placed in reverse gear position.

\ erence'will be had to the accompanyin 3 is a section on- 1ine'3.-3 of Fig 'ure 1.

. This invention also consists in certain other features of construction and in the combination and arrangement of the several parts,

to be hereinafter fully described, illustrated in the accompanying drawings and specifically' pointed out in the appended claims.

In describing-my invention in detail refings' wherein like characters denote ike or corresponding parts throughoutthe several views, and in w ich I Figure 1 is a sectional view showing the device placed between the transmission means and the universal joint.

Figure 2 is a section on line 2-2 of'Figure 1.

In these drawings, 1 indicates a housi placed between the transmission housin an the universal joint and havin 'bearin t ere-' in for the transmission'sha --2 wh1ch is of greater length than the regular transmission shaft so that the shaft will extend throu h sleeve -5. A block 6 is slid the housing 1 A sleeve 4 is arranged in t e housi 1 and is keyed to the shaft 2, this heing provided with the spiral teeth iibly arranged in the housing 1-, the side walls of the housing being machined so that the block can have free sliding movement therein. This block is provided with a central opening to receive the sleeve'and the walls of the opening are formed with the s iral notches 7 for receiving the teeth 5. grooved collar 8 is fastened to the rear face of the block and surengaging the groove in the collar. This fork 1S fastened to 'a plunger'rod 10 arranged in Y bears against. the fork and a ainst the inner end' of a nut member 13 whic surrounds the rear end of the rod and is threaded in a holAe lock nut 14 holds the member 13 in ad usted position. U

raw-

29., 1927. Serial No. 256,518.

tends to press the plunger rod and the fork forwardly and thus causes the forkto move the collar 8 and the block 6 against the teeth 5 so that if the shaft 2 starts to turnin a reverse direction, the teeth will enga e the notches in the block and thus the -shaft2 will be locked against movement in a reverse directlon. This, of course, will prevent therear wheels of thevehicle from movin rearwardly and thus it will be impossible or the vehicle. to move or roll backwardly. 4 The spiral teeth and notches areso. formed as to interen gage each other when the shaft 2 moves in areverse direction.v When the shaft turns in the other direction, the rear ends of fro t and rear of the, housing to prevent lubricant lacedin the housing ,from leaking out. The h using is adapted to be fastened toa part 0 the frame,as-shown at 17, and it is" providedwvith a removable cover 18.

' From the foregoin it will be seen that the device automatica 1y prevents a vehicle from rolling backwards when the in any posltion other than reversing position, but as soon as the gear shifting lever is placed in reverse position, the device is moved to neutral osition so that it will not interfere with t e backward movement of the vehicle'. With thisinvention, a car may stop on any grade or incline and be left there without an chance of the brakes failing and the car ro ling backwardly. As soon as the car starts forwardly, the left hand spirals will push the block rearwardly as they leave the aft hand spiral notches if the car has moved. backwardly to place the locking device in locking osition.

It is t ought from the foregoin description that the advantages and novel features of my invention will e readily apparent.

It is to be understood that I ma make changes in the construction and in t e-comgears are parts, provided that such changesfall within the scope of the appended claims.

What I'claim is 1. A back stop for motor vehicles comprising'a member having left hand spiral teeth thereon attached to'a drive shaft'of the vehicle, a slidable member having'left hand spiral-notches therein, means for holding the notched member against rotary movement while permitting it to have sliding movement, yieldable means for holding the slidin member against the first member where y the teeth of the first member will enter the notches of the sliding member when the shaft is moved in'a reverse direction so as to cause the sliding member to lock the shaft against movement, the ends of the teethsliding over the end of the sliding member when "the shaft is turning in an opposite direction,

and means for moving said member into neutral positionwhen the shifting lever of the vehicle has been moved to reversing position.

2. A back stop for a motor vehicle comprising a housing placed in rear of the transmission housing and receiving a part of the transmission shaft, a sleeve keyed'to the shaft and arranged within the housing, left hand spiral teeth on the sleeve, a member arranged in the housing and surrounding the sleeve and havin left hand spiral notches therein for receiving the teeth, the sides of the member bearing against the sides of the housing to prevent rotary movement thereof while permitting sliding movement, a grooved collar connected with the member, a plunger rod arranged in the .top part of the housing, a fork carried thereby and having its prongs engaging the groove in the collar, means for .holding the plunger in a forward position to cause the sliding member to engage the spiral teeth, said plunger being pushed rearwardly when'the shifting lever of the vehicle is in therein for receiving the teeth, the sides of themember bearing against the sides of the housing to prevent rotary movement thereof while permitting sliding movement, a gi-ooved collar connected with the member, a p unger rod arranged in the top part of the housing,- a fork carried thereby and having its prongs engaging the groove in the collar, a spring for holding the-plunger in a forward position to cause the sliding member to engage the spiral teeth, said plunger being pushed rearwardly when the shifting lever of the vehicle is in reversing position and means for adjusting the tension of the spring.

In testimony whereof I affix my signature.

PHILLIP L. LACY 

